1. Field of the Invention
The invention lies in the field of instrument systems designed to match an optronic system mounted on a helmet with the particular morphology of the helmet wearer. This matching constitutes the procedure for the customizing of the helmet. Such helmets are used particularly in military aeronautics.
Head equipment in military aeronautics consists essentially of the helmet whose primary function is to protect the pilot. The helmet is also used as a support for breathing and hearing instruments, and for a display system that provides the pilot with information by means of an image source (cathode-ray tube, liquid crystal matrix etc.) and an optical collimation system.
The helmet has to be designed for and matched with the pilot's morphology to provide for the optimal use of the head equipment. The matching of each helmet with its wearer's morphology is done during the customizing procedure. During this procedure, the helmet has to be positioned and oriented very precisely in relation to anatomical reference points of the subject.
2. Description of the Prior Art
In the current state of the art, the customizing procedure calls for several operations for the precise identification of the pilot's morphology. The manufacture of the helmet can be done on the basis of this morphological information, but these operations are lengthy and imprecise because of the difficulty of making precise measurements of the characteristics of the head.
Other procedures call for active participation by the subject so that he or she positions his or her head with respect to precise reference points on the helmet or on an associated instrument system. During these procedures, there is a risk that the pilot might take up uncomfortable postures that do not correspond to functional positions that he or she will take up when using the equipment. These constraints in particular harm the subsequent efficiency of the display system which will be mounted on the helmet.
The aim of the customizing procedure is to place two optical diaphragms, a first diaphragm and a second diaphragm, in one and the same plane P. The first diaphragm is constituted by the pupil of the helmet wearer's eye. The second diaphragm is the pupil of the optical system that will be mounted on the helmet. This pupil of the optical system is in a plane P that has no physical existence but whose theoretical position is known in relation to reference points taken on the helmet, for example fastening points of the optronic display system.
It is imperative that the optical pupil of this system should be placed in the same plane as the pupil of the wearer's eye and that the two diaphragms constituted by the two pupils should be centered on each other when the subject looks in a reference direction u. This direction is generally represented by a collimated target and is located in a horizontal plane passing through the line of the wearer's eyes during the customizing procedure.
The aim of the invention is to simplify and shorten the customizing procedure. The aim is also to preserve, for the wearer, a degree of ease and comfort during this procedure that is at least equal to the ease and comfort that he or she will enjoy when he or she is fully fitted out. Finally the aim is to improve the positioning precision of the helmet.